When the final horn sounded Friday night and the offseason crept closer, John Carlson glided his skates across the ice, because his skates are always on the ice. He didn’t bend at the waist, like some of his absolutely gassed Washington Capitals teammates did, though he had surely earned the right. He shifted his weight and skated to the bench, then walked to the home dressing room at Capital One Arena, where the battered team he’s trying to hold together gathered for what might be the penultimate time.